var Moment = function (date) {
    var date;
    if (date)
      this.date = new Date(date);
    else
      this.date = new Date();
    return this;
  };
  /**       
   * 对Date的扩展，将 Date 转化为指定格式的String       
   * 月(M)、日(d)、12小时(h)、24小时(H)、分(m)、秒(s)、周(E)、季度(q) 可以用 1-2 个占位符       
   * 年(y)可以用 1-4 个占位符，毫秒(S)只能用 1 个占位符(是 1-3 位的数字)       
   * eg:       
   * "yyyy-MM-dd hh:mm:ss.S" ==> 2006-07-02 08:09:04.423    
   * "yyyy-M-d h:m:s.S" ==> 2006-7-2 8:9:4.18       
   * "yyyy-MM-dd E HH:mm:ss" ==> 2009-03-10 二 20:09:04       
   * "yyyy-MM-dd EE hh:mm:ss" ==> 2009-03-10 周二 08:09:04       
   * "yyyy-MM-dd EEE hh:mm:ss" ==> 2009-03-10 星期二 08:09:04  
   */
  Moment.prototype.format = function (format) {
    var date = this.date;
    /*
        var r= /^(\d{4})-(\d{1,2})-(\d{1,2})$/; //正则表达式 匹配出生日期(简单匹配)     
        r.exec('1985-10-15');
        s1=RegExp.$1;s2=RegExp.$2;s3=RegExp.$3;//结果为1985 10 15
        */
    if (typeof date === 'string')
      date = this.parse(date);
    var o = {
      "M+": date.getMonth() + 1, //月份 
      "(d+|D+)": date.getDate(), //日 
      "(h+|H+)": date.getHours(), //小时 
      "m+": date.getMinutes(), //分 
      "s+": date.getSeconds(), //秒 
      "q+": Math.floor((date.getMonth() + 3) / 3), //季度 
      "S": date.getMilliseconds() //毫秒 
    };
    var week = {
      "0": "/u65e5",
      "1": "/u4e00",
      "2": "/u4e8c",
      "3": "/u4e09",
      "4": "/u56db",
      "5": "/u4e94",
      "6": "/u516d"
    };
    if (/(y+|Y+)/.test(format))
      format = format.replace(RegExp.$1, (date.getFullYear() + "").substr(4 - RegExp.$1.length));
    if (/(E+)/.test(format))
      format = format.replace(RegExp.$1, ((RegExp.$1.length > 1) ? (RegExp.$1.length > 2 ? "/u661f/u671f" : "/u5468") : "") + week[date.getDay() + ""]);
    for (var k in o) {
      if (new RegExp("(" + k + ")").test(format))
        format = format.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
    }
    return format;
  }
  
  Moment.prototype.parse = function () {
    return this.date;
  }
  /**
   * 计算两个日期差差
   * return day
   */
  Moment.prototype.differ = function (date) {
    var time1 = this.date.getTime();
    if (typeof date === 'string')
      date = new Date(date);
    var time1 = this.date.getTime();
    var time2 = date.getTime();
    var differ = Math.ceil((time1 - time2) / (1000 * 3600 * 24));//除不尽时,向上取整
    return differ;
  }
  
  Moment.prototype.add = function (num, optionType) {
    var date = this.date;
    if ('day' === optionType) {
      date.setDate(date.getDate() + num);
    }
    if ('month' === optionType) {
      date.setMonth(date.getMonth() + num);
    }
    if ('year' === optionType) {
      date.setFullYear(date.getFullYear() + num);
    }
    this.date = date;
    return this;
  }
  
  Moment.prototype.before = function (date) {
    return this.date.getTime() < new Date(date).getTime()
  }
  Moment.prototype.after = function (date) {
    return this.date.getTime() > date.getTime()
  }
  
  module.exports = function (date) {
    return new Moment(date);
  }